Electronic high-voltage generator discharge device



March 15, 1949. A. SAMUEL 2,464,349

ELECTRON IC HIGH-VOLTAGE GENERATOR DISCHARGE DEVICE Filed May 27, 1943.mmm 1M 36 87 III III lNl/EN r01? A L SAMUEL Lv-JW A T TORNE V PatentedMar. 15, 1949 ELECTRONIC HIGH-VOLTAGE GENERATOR DISCHARGE DEVICE ArthurL. Samuel, Summit, N. 3., assignor to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation of New York Application May27, 1943, Serial No. 488,626

6 Claims.

This invention relates to electron beam devices, particularly thoseoperating at ultra-high frequencies and utilized to produce highvelocity electrons or high electric potentials.

A principal object of the invention is to provide a self-containedsource of high velocity electrons which may be used to produce X-rays orfor other purposes.

Another object is to provide a self-contained electronic source of highunidirectional potential.

A feature of the invention is that elaborate auxiliary apparatus is notrequired.

Another feature is that the external energy supply source need not .beof extremely lfigh potential.

An additional object is to provide a device of the type desired which isstructurally compact.

It is known in the art to accelerate electrons by means of highfrequency fields. Examples are the well-known cyclotron and the X-raydevice of Sloan described in U. S. Patent 2,009,457. Also a device moreclosely related to the present invention which is aranged to produce ahigh voltage or high velocity electrons by first increasing thepotential energy of the electrons without accelerating them is disclosedin a co-pending application of A. M. Skellett, Serial No. 377,458, filedFebruary 5, 1941 and issued as United States Patent 2,407,296, September10, 1946.

These and other similar devices require for their operation highfrequency energy from an external source which is appropriately appliedto electrodes of the device and of which the freucncy must be properlycorrelated with the structure and adjustments of the device.

In the applicants device to be described no external high frequencysource is required. The high frequency is generated within the deviceitself and correlation between the high frequency energy and the meansfor its use is inherent in the design as the electron beam and the highfrequency circuit are common to both the high frequency generating andutilizing means.

The detailed features of the device and the method of operation will beapparent from the following description and the accompanying drawingsWhile the scope of the invention is defined in the appended claims.

In the drawings:

Fig. 1 shows a form of the invention as arranged to produce a highvelocity electron beam;

Fig. 2 shows an alternative arrangement for the production of a highvelocity electron beam, difiering from Fig. 1 principally in the use ofresistors to distribute electrode potentials; and

Fig. 3 shows a modification of the device of Fig. 2 to produce atsuitable terminals a high unidirectional potential.

With reference to Fig. 1. Within the evacuated envelope l are located acathode 2, an electron accelerating electrode 3, a series of generallytubular electrodes 4, 5, 6, l, 8, 9, 10, ll, l2 and I3 defining the gapsor spaces [4, I5, [6, l1, it, i9, Z6, 2! and 22 and a target andcollecting electrode or anode 23. The electrodes 4 to l3 inclusive aresupported by the metallic discs 24 to 33 inclusive sealed into theenvelope l as has been shown also in U. S. Patent 2,281,717 issued tothe applicant on May 5, 1942. Metallic member 35 is shown as cylindrical(though it may be of any suitable shape) with annular ends which connectwith the discs 24 and 33 to enclose a space 35 and form a hollowelectrical resonator. This resonator is bounded by the member 3%, discs24 and 33 and the electrodes 4 to l3 inclusive. The portions of spacewithin the electrodes 4 to is are shielded from the resonator space 35and are therefore external to the resonator space. The high frequencyfield associated with the resonator When it is energized extends intothe spaces or gaps i l to 22 where it may interact with an electron beamtraversing them along the path between the cathode 2 and the target 23.The cathode Z is suitably heated by energy from source 36 to emitelectrons which may, under the influence of the electrodes 3, 4, 5, 6, land it (positively charged from source 31), flow through the electrodes4 to l3 and gaps [4 to 22 to the target 23.

It will be observe-d that the electrodes 5, 6 and l are maintained atthe same direct potential as the resonator shell (or boundary) and theelectrodes :3 and I3 attached thereto by the connections 38, 39 and 40.These connections are preferably of small dimensions (they may berelatively small wires) and should extend substantially radially inorder to minimize interference with the electromagnetic waves within theresonator. If it is desired to make the potentials of these electrodesdifferent from that of the resonator shell the leads 38, 39 and 40 maybe passed through holes in the shell and connected to an externalpotential source. The resonator shell, the electrodes 4 to 1 and themeans for projecting an electron stream through the gaps it, Hi and Itconstitute a multigap oscillator whereby the resonator may be energizedat its resonant frequency. This type of oscillator, with three gaps, hasbeen shown in Fig. 1 of the applicants copending application, Serial No.

412,067 filed September 24, 1941 and issued as United States Patent2,403,025, July 2, 1945. The same type of oscillator utilizing two gapshas been shown in Figs. 1 and 5 of the copending joint application ofthe applicant and A. E. Anderson, Serial No. 386,794 fil April 4., i941and issued asUnlted States Patent [5,405,175, August 6, 1946. Variousnumbers of gaps may be utilized in such an osc; -ator. In, 1 three gapsM, 35 and it are shown in the oscillator portion of the device. Agreater or less number may be used depending upon what may be requiredto produce the necessary high frequency energy or for best operation ofdevice as a whole. oscillator portion operates as described in thecopending application, Serial No. 386,79 referred to above and itsfunction is to produce the high frequency field in the resonator wherebysome of the electrons attain high potential energy and may be highlyaccelerated. An oscillator operating on the same principle is describedalso in U. 3. Patent 2,222,902, issued November 26, 1940, to W. C. Hahnwherein it shown that to obtain high frequency power the electrontransit time between gaps should be a period which is that of anintegral number of cycles of the high frequency less a fraction of aquarter of a cycle depending upon the number of gaps.

Electrodes 8 to l2 inclusive not used in the oscillator portion of thedevice are left floating, connected to each other and the rest of thestructure only by leakage resistances. Under that con dition theseelectrodes will become negatively charged with respect to the rest ofthe system,

electrodes becoming progressively more negative in the direction of thelast electrode it. Each of these electrodes, then, is negative withrespect to the one preceding it (electrode 8 is negative with respect toelectrode 7 and electrode 9 is negative with respect to electrode 3 andso on) and the direct potential so impressed across each of the gaps llto El inclusi oroduces there, superposed upon the high fr encyunidirectional electric field tending to retard the flow of electrons.Electrons crossing the gaps must do so by virtue of their velocity andassisted by the high frequency field when it is in the proper phase tooppose this unidirectional retarding field. This unidirectional fieldexisting in each of the gaps ll' to'Zl inclusive may be considered as asingle stepped unidirectional field extending from electrode 7 toelectrode l2. The term stepped is applied here because the potentialdoes not change uniformly along the electron path but in-steps at thegaps H to M and the electrons acquire a low potential in a number ofsteps as they traverse the of electrodes as will now be explained.

In the oscillator portion of the system velocity variations areimpressed upon the electron beam andat least some of the electronshaving various velocities will pass through electrode 1. Certain ofthese electrons will enter gap ll at such a phase of the high grequencyfield of the resonator as to tend to be accelerated by it and be therebyenabled to reach the interior of the first negatively charged electrode8. Some of these electrons will drift through electrode 8, be againpropelled by the high frequency field in gap l8 and be enabled to reachthe interior of the still more negatively charged electrode 9 and so onthrough the rest of the electrodes up to electrode l2. It will be notedthat a cumulative effect of the high frequency field on the electrons inthe (ill gaps H to 2!, inclusive is desired so that the electronvelocity and the lengths of the electrodes 8 to 2 should be such thatthe electron transit time between the gaps is approximately the periodof one cycle of the high frequency or of any whole number of cycles. Theelectron transit time through an electrode in this part of the devicemay therefore be somewhat longer than it is in the oscillator portion.Certain of the electrons finally reaching the interior of the highlynegatively charged electrode l2 may then pass through the gap 22 at veryhigh velocity under the influence of the positively charged electrodeit. These high velocity electrons emerging from electrode 53 then maystrike the target anode'23 to produce X-rays or may be utilized in anydesired manner.

It may be noted that all of the electrons in the beam leaving thecathode do not reach the target, so that the action of the device may belikened to that of a hydraulic ram in that a large number of electronsunder the influence of a relatively low accelerating potential cause apart of those electrons to come under the influence of a much higheraccelerating potential. This high accelerating potential is produced bysuccessively depressing the potential of the higher velocity electronsby forcing them through the series of retarding electrostatic fields inthe gaps H to M. The electrons finally leave the most negative electrode52 under the influence of the high accelerating potential betweennegative electrode 22 and positive electrode 53. It may be further notedthat in the operation of the entire device the net effect in theoscillator portion (comprising gaps Hi, l5 and i6) is the generation ofhigh frequency energy to excite the resonator to produce the highfrequency field which extends into the gaps between the electrodes whilein the part of" the device comprising gaps I! to 2i inclusive the neteffect is to store energy in the electron stream by successivelydepressing the potential of the electrons which continue along the path.In other words, in the oscillator portion, preponderantly, energy istransferred from the electron stream (energized from the relatively lowpotential source fall) to the high frequency field and further along theelectron path of the device, preponderantly, energy is transferred fromthe high frequency field to the electron stream in the form of potentialenergy. This potential energy may be used to effect a high accelerationof the electrons as in Fig. 1 or to provide a high potential directcurrent source as in Fig. 3 which will be explained later. Thus theremay be produced within the device itself direct current energy at a veryhigh potential while operation of the device is from a power source ofmuch lower potential as indicated at 31 in the figures.

Fig. 2 shows a modification of Fig. 1 in which the electrodes not usedin the oscillator portion of the device are not left completelyinsulated except for possibly uncertain leakage resistance but areconnected together and to ground with high resistance resistors to moredefinitely divide between them the high negative potentials developeddue to the accumulation of charges upon them. This particular feature isshown in the somewhat similar device disclosed in the abovementionedcopending application Serial No. 377,- 458 filed February 5, 1941 by A.M. Skellett.

In Fig. 2 the envelope E, cathode 2, electrodes 3 to ill and the rings 2to (it are the same as in Fig. 1. However, the resonator shell member 3dof Fig. l is divided into a number of parts 52 to 51. For highfrequencies these parts form a continuous conducting shell enclosing thespace 35 by virtue of the capacitances between the spaced flanges 58which are provided for that purpose. For direct potentials the shellportions 52 to 51 are insulated from each other except for theconnections through the high resistances 45 to 5|. The electrodes 5, 6and l which function in the oscillator portion of the device areconnected to the shell portion 52 and so to the source 31 by leads 38,39 and to as in Fig. 1. Electrodes 8 to I2 (which are floating inFig. 1) and iii are connected through leads M to 5 and resistors 46 to5| to the source til and ground. The leads 42 to 45 connect also to theresonator shell portions 53 to 56, respectively so that these shellportions acquire the same potentials as the electrodes 9 to l2,respectively. This is a design feature to facilitate insulating thestructure for the high potentials developed but is not essential. Toshow an alternative method of construction the lead 4! connecting toelectrode 8 is shown passing through an opening 59 in the shell portion52 and the part of the portion 52 radially outward from electrode 8 isnot isolated by spaced flanges (such as 58) as are the portions 53 to5'! radially outward from electrodes 9 to l3. An alternativeconstruction therefore is to use a shell member such as 36 in Fig. 1without the flanges 5B and pass all of the leads M to G5 to theresistors 46 to 51 through openings such as 59. It is obvious thatordinarily when the spaced flange type of construction illustrated inFig. 2 is employed the shell would be further sectionalized oppositeelectrode 8 by another .pair of flanges and the opening 59 would notthen be required as lead 4| would connect with an isolated shell portionthe same as leads 4'12 to 45. As mentioned above the resistors it to Elserve to equalize the distribution of voltage between the electrodes.They are made high enough, however, to permit the electrodes to becomecharged to relatively high potentials with small current flow in them.

Operation of the Fig. 2 arrangement is the same as that of Fig. 1, theelectron stream generating high frequency energy in the resonator in theoscillator portion of the device comprising gaps M, l5 and I6 and thehigh frequency field of the resonator in turn acting upon the electronstream in the other portion of the device comprising gaps H to 22 toproduce high accelerating potentials and high velocity electrons.

It may be noted that in Fig. 1 the electrode [3 is at the same potentialas the cavity shell and the target 23 so that the electrons are highlyaccelerated between electrodes :2 and I3 while in Fig. 2 the electrodei3 is isolated in the same manner as electrodes 8 to l2 so that itbecomes the most highly negatively charged electrode and the electronsare accelerated between the electrode I3 and the target 23. In eithercase high velocity electrons strike the target 23.

Fig. 3 shows a device like that of Fig. 2 but arranged to utilize thehigh voltage developed rather than high velocity electrons. An electroncollector 50 to serve as an anode is substituted for the target 23 andis connected to electrode l3 and resistor 5| through an additionalresistor 53. The collector is not connected directly to ground andsource 31 as was the target 23, but rather, through the resistances andtwo terminals (6! connected to the collector and 52 connected to groundand source 31) are provided between which the high direct potentialdeveloped is available for any desired use.

Operation of the arrangement of Fig. 3 is similar to that of Figs. 1 and2 in that there is an oscillator portion of the device comprising gapsM, 5 and i5 and a portion where the high frequency field of theresonator propels certain of the electrons through the retarding fieldsof the series of negatively charged electrodes 8 to l3 and 66 so thatacross the Whole series a potential much higher than that of the source3? is produced. The essential difierence between this Fig. 3 arrangementand that of Figs. 1 and 2 is that this high potential is impressedacross the high resistance iii to El and 63 and may be utilized directlyat the terminals 6i and 62 whereas in Figs. 1 and 2 the high potentialis employed in the device to produce high velocity electrons which maybe utilized to produce X-rays or for any other desired purpose.

In the previously mentioned copending application Serial No. 377,458 adevice is shown for producing a high potential by a method somewhatsimilar to that employed in Fig. 3. However, that device does notinclude means for generating with the electron beam the high frequencyenergy required.

it may be noted that in Figs. 1 and 2 the lead from the target 23 and inFig. 3 the lead from terminal 62 may, if desired, be connected to thecathode directly rather than to ground and thence to the cathode throughthe source 3'! as shown. If connected to the cathode directly theaccelerating potential or the potential at the terminals iii and 62 willbe increased by the potential of source 37.

What is claimed is:

1. An electronic device comprising means for producing an electron beam,a plurality of generally tubular electrodes in axial alignment therewithspaced from each other and adapted to be 0 axially traversed by theelectron beam and a hollow electrical resonator having a shell whichincludes the said spaced electrodes and which when excited impresses ahigh frequency field to interact with the electron beam in the axialspaces between the said electrodes, some of the said electrodes adjacentto each other being electrically interconnected by leads having lowdirect current resistances and others of the said electrodes adjacent toeach other are electrically interconnected through paths having directcurrent resistances substantially higher than the resistances of saidlead interconnections.

2. An electronic device comprising an evacuated envelope including meansfor producing a high frequency electric field within said envelope,including means for projecting a beam of electrons along a path Withinsaid envelope through said field whereby the electrons in the beam mayinteract with the electric field, and a plurality of shielding means ofconducting material spaced along the electron path within the saidenvelope whereby the electron beam is shielded from the high frequencyfield except at the spaces between the shielding means, a plurality ofthe said shielding means adjacent to each other along one portion of theelectron path being interconnected by leads having low direct currentresistances and another plurality of the said shielding means alonganother portion of the electron path being interconnected by pathshaving direct current resistances substantially higher than said lowresistances.

3. An electronic device comprising, an electron tube having a cathode,an anode and a plurality of electrodes in spaced relation between theoathbetween the electrodes, some of the said electrodes located in theregion toward the cathode and adjacent to each other being electricallyinterconnected by leads having low direct current resistances and othersof the said electrodes located in a region nearer to the anode andadjacent to each other being electrically intercon nected through pathsof direct current resistance substantially higher than said lowresistances, the lengths of the said electrodes as measured along thesaid electron path corresponding to an electron transit time betweencorresponding points on adjacent electrodes of substantially beta/ eenthe periods of n+% and n+1 cycles of the said resonant frequency where nis an integral number of cycles including zero.

tube having a cathode, an anode and a plurality of electrodes in spacedrelation between the oathode and anode, and including means forprojecting a beam 01 electrons from the cathode to the anode along apath in proximity to the said spaced electrodes and the spacestherebetween, a hollow electrical resonator capable of being excited atits resonant frequency by the electron beam and the boundary of whichincludes the said spaced electrodes, whereby a high frequency field mayinteract with the electron beam in the said spaces between theelectrodes, some of the said electrodes located in. the region towardthe cathode and adjacent to each other being electrically interconnectedby leads having low direct current resistances and having lengths asmeasured along the said electron path corresponding to an electron.transit time between corresponding points on adjacent electrodes ofsubstantially between the periods of n+% and n+1 cycles of the saidresonant frequency where n is an integral number of cycles includingzero and others of the said electrodes located in a region nearer to theanode and adjacent to each other are electrically separated by pathshaving direct current resistances substantially higher than said lowresistances and have lengths as measured along the said electron pathcorresponding to an electron transit time between corresponding pointson adjacent electrodes of substanthially the period of 12-1-1 cycles ofthe said resonant frequency where n is an integral number of cyclesincluding zero.

Number 5. An electronic device comprising an :evacuated envelopeincluding means for producing a high frequency electric field withinsaid envelope, including means for projecting a beam of electrons alonga path within said envelope through said field whereby the electrons inthe beam may interact with the said electric field and a plurality ofshielding means of conducting material spaced along the electron pathWithin the said envelope capable of collecting electrons and ofshielding the electron beam from the electric field except at the spacesbetween the .shieldin means, a plurality of the said shielding mean?adjacent to each other along one portion of the\ electron path havinglow direct current resistance interconnecting leads and anotherplurality of the said shielding means along another portion of theelectron path having substantially higher direct current resistanceinterconnecting electrical paths.

6. An electronic device comprising an electron tube havin a cathode, ananode and a plurality of electrodes in spaced relation therebetween,means comprising a source of direct current potential connected to thecathode for projecting a 4. An electronic device comprising, an electronbeam of electrons from the cathode along a path in proximity to the saidspaced electrodes and the spaces therebetween, a hollow electricalresonator capable of being excited at its resonant frequency by theelectron beam and which includes the said spaced electrodes whereby whenthe resonator is excited there is impressed a high frequency electricfield to interact with the electron beam in the said spaces between theelectrodes, some of the said electrodes in the region toward the cathodebeing connected by leads for direct current to the said potentialsource, others of the said electrodes farther along the electron pathfrom the cathode having direct current paths which include substantialresistance between each other and between them and the said potentialsource.

ARTHUR L. SAMUEL.

REFERENCES IETED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date 2,222,902 Hahn Nov. 26, 1940 2,281,717Samuel May 5, 1942 2,284,751 Linder June 2, 19-1 2 2,325,865 Litton Aug.3, 1943 2,407,298 Skellett Sept. 10, 1946 OTHER REFERENCES Proc. I. R.E.--Feb. 1939, vol. 27, No. 2, page 114.

